Split flow mass flowmeter transducers for obtaining ongoing measurement of fluid flow rate generally operate on the principle of directing fluid flow through two parallel passageways, paths or branches, one of which is utilized as a sensor tube for measuring the mass flow rate of the fluid while the other comprises the primary flow path for the main or non-measuring branch of the meter. The sensor tube is locally heated and measurement is dependent on maintaining a consistency of flow rates between the two branches such that a signal thermally obtained from the sensor tube will accurately reflect the flow rate through the meter as a whole. Thermal measurement in such systems operates on the principle that for a given fluid having a known density, viscosity, specific heat, etc., heat will be absorbed at a fixed rate that is dependent on the mass flow of the fluid passing the heat source per unit of time. Flowmeters of this type are exemplified by the disclosures of U.S. Pat. Nos. 3,792,609 and 4,056,975.
While such constructions are commercially marketed and are well regarded by the consuming public, they are generally characterized as being slow to respond to changes in flow rate occurring within the meter. This is believed attributed to thermal characteristics of the sensor tube caused by axial conduction of heat through the tube wall to relatively long inactive sections of the tube. As a result, long time delays are incurred in reaching equilibrium temperature distribution as changes in flow rate occur. One approach for overcoming the foregoing has been to enhance measurement response by varying the power input to the meter and thereby maintain a more constant temperature profile about the sensor tube. While reasonably effective, the approach is relatively costly to implement and tends toward a non-linear output which must subsequently be linearized. Despite recognition of the problem, a ready solution thereto has not heretofore been known.